The present invention relates to a fastening method for a fastening bolt of a sub frame to car body and a sub frame rigid collar for car used for the fastening method.
The mass-produced four wheel car in the conventional car puts a power system and a drive system on a sub frame and is assembled to a monocoque chassis (body).
In this case, the body and the sub frame are fastened by a bolt, and in order to improve the work efficiency, a clearance (gap) is provided to a hole extended through the sub frame and a hole of the screw at the body side.
That is, an example thereof is shown in FIG. 14.
An introduction hole 3 to a screw hole 2 of a fastening bolt 10 of a monocoque body 1, and a through-hole 5 of the fastening bolt 10 of a sub frame 4, are provided with the introduction hole 3 having 16 mm diameter larger than the outer diameter of the fastening bolt 10 of for example, 14 mm and the through-holes 5 having diameter larger than therefrom.
This clearance exists commonly from a light duty vehicle to a passenger car, a sports car, and a high-level large-scale vehicle in a mass production vehicle all over the world.
Recently, the stiffness in the body unit has risen rapidly. However, no matter how the body unit is very high stiffness, the generation of “shaking” heterogeneous phase is undeniable by the existence of the clearance concerning the fastening condition with the sub frame, this influences the decrease in the resonant frequency of the body, so that it is a big problem and is an encumbrance that negatively affects the control performance, in particular, handling, riding comfort, quietness, and the collision safety.
As the means to resolve the problem of such clearance, it is developed and proposed the method of interposing a bush.
For example, in JP 2005-90530, A (patent document 1), the invention of “Locking fastening structure of plural stacking members” is disclosed.
As shown in FIG. 15, the thin wall portion of an inverted cone body having an eccentric through-hole 59 larger than the nominal diameter of the bolt 52 a little, is involved to a bush 58 which provides in file a segmental slit 51, and is provided with an inverted cone hole 51 having the taper plane of the same inclined angle as the inverted cone inclined angle of the bush 58 is punched onto the upper portion of the bolt through-hole 56 from the plane of the fastened member 54 at the side where a bolt head 52a abuts thereto, thereby fastening the fastened member 54 in the conditions of interposing the bush 58.
The technology similar thereto is disclosed in JP 3733534 as “Locking fastener” (patent document 2).